U.S. Pat. No. 5,250,233 discloses a carburetor having an accelerator pump. The pump has a pump piston which is coupled to the position of the throttle shaft. When the throttle flap is displaced from the idle position into the full-load position, the pump piston executes a pump movement and conducts additional fuel to the intake channel. In this way, a leaning of the mixture when accelerating is intended to be avoided. During the transition from the full-load position of the throttle flap into the idle position, it can occur that the internal combustion engine does not drop immediately to the adjusted idle rpm; rather, the engine still stays at the higher rpm for some time.